Voltammetric determination of amlodipine besylate in human urine and pharmaceuticals

Electrochemical determination of amlodipine besylate (ADB) using single and multi-walled carbon nanotubes modified edge plane pyrolytic graphite electrodes (SWNT/EPPGE and MWNT/EPPGE) is described by using cyclic and square wave voltammetries at physiological pH 7.2. An increased peak current with a shift of peak potential to less positive value was observed using carbon nanotubes modified EPPGE as compared to bare electrode. The effect of pH, scan rate and analyte concentration has been examined. Under the optimum conditions the peak current was linear to the concentration of amlodipine in the range 5.0 x 10(-9) to 1.0 x 10(-6) mol L-1 for SWNT/ EPPGE and the detection limit was found to be 1.0 x 10(-9) mol L-1 whereas, for MWNT/EPPGE the detection limit was found to be 5.0 x 10(-9) mol L-1. The method was successfully used to determine the content of amlodipine in the pharmaceutical preparations and human urine samples of angina patients undergoing treatment with amlodipine. A comparison of electrocatalytic activities of SWNT and MWNT modified electrodes indicated that SWNT modified EPPGE is similar to 1.8 times more sensitive in comparison to MWNT/EPPGE. Biological relevance of the developed method has been described by the determination of amlodipine in human body fluids. Amlodipine can be determined without any interference from common urine metabolites such as uric acid, ascorbic acid and xanthine. (C) 2010 Elsevier B.V. All rights reserved.